Hydraulic metal drawing press and method for shaping metal articles



May n? 1936- w. ERNST A I 2,040,731l 'Y HYDRAULIC METAL DRAWING PRESSAND METHOD FOR SHAPING METAL ARTICLES Filed Jan. 2,- 1929 s sneetsfsheet1 mvenfor v Gttornegs,

May 12, 1936. w. ERNST 2,040,731

HYDRAULIC METAL DRAWING' PRESS AND METHOD FOR SHAPING METAL ARTCLS FiledJan. 2, 1929 3 Sheets-Sheet 2 j, Envenktor,

Gttornegs.

w. ERNST 2,040,731

HYDRAULIC METAL DRAWING PRESS AND METHOD FOR SHAPING METAL ARTICLES May12., 1936.

Filed Jan. 2, 1929 3 Sheets-Sheet 3 UNITED ,STATES PATENT oFElCEHYDRAULIC METAL DRAWING' rREs's AND METHOD Foa snAPING METAL ARTICLESWalter Ernst,-Mount Gilead, Qhio, assigner, by mesne assignments, to TheHydraulic Press Corporation, Inc., Wilmington, Del., a corporation ofDelaware 4 Application January 2, 1929, Serial No. 329,765

22 Claims. (Cl. 113-45) Thisinvention relates to hydraulic drawingpresses and more particularly to drawing presses including male andfemaledies, one of whichis attached to a stationary table fixed to thepress frame-and the other of which is carried by a platen mounted on thepress frame for reciprocatory movements towards and away from thestation- I ary die, and in which press there is provided a'hydraulically operated die cushion for clamping the work against themoving die and thus holding the work in proper position relative to thedies "during the drawing operation.

When shaping metal into Various forms by the drawing process, it iscustomary Ato employ a pair: ofdies consisting of a female die and amale die,

one being fixed to a stationary part of a press and the other beingcarried by the press platen and adapted to move towards and away fromthe fixed die so-that the male die enters the female die and shapes ordraws a blank placed on the xed die to the desired form. When thedrawing operation requires -what is known as a' deep draw, there is a.tendency for the blank to wrinkle. In order to overcome this tendency,various devices known as blank holders have been used to yieldinglyclamp the blank against the female die. Some of these previously usedblank hold- 4 rs have been operated by mechanical means lncluding linksand toggles, others by spring loaded 0 devices, and still others by airor hydraulic pressure loaded pistons or rams. The `chief disadvantage ofall such devices heretofore used is that, each time the nature of thedrawing operation is changed, as, for instance, when a heavier 5 orlighter blank is-to vbe drawn, or when a dinerent set of dies is to beused, the blank holdlerv operating means must be adjusted so that theblank holder will clamp the blank under a pressure best suited fortheparticular drawing opera'.-

tion to be performed. l

.'I'he main object of the present invention is to provide in a drawingpress a die cushion, or blank holder, so arranged that the pressureexerted by 45 the blank holder will always bear a constant ratio to thepressure exerted on the blank by the moving die, so that the blank willautomatically" be clamped against 4the female die under onlyl suchpressure as is necessary for preventing 50 wrinkling-of the blank'. y

Among other objects of the invention are tol provide a press for drawingmetal adapted to ausmtomajlgally perform an indeterminate number ofdrawing opitionsateashigh speed. and to pro- 55 vide such a press inwhich the speed of the mov- (191.'7, granted vto Hele-Shaw et al.`

ing die is automatically reduced as the resistance to drawing increases.y

v With these and other objects in view, the nature of which will morefully appear, the invention will b e understood from the followingdescription, the 5 appended c1aims,and the several views illustrated linthe drawings, in which: t

Figure 1 is a front elevation of a hydraulic press, showing someessential operating parts thereof, some parts being shown in section; 10

Figure 2 is an enlarged partial Iside elevation taken at right angles toFigure 1, 'with certain parts shown in section; l

Figure 3 is a fragmentary vertical sectional view of the lower portionof the press, drawn on 15 an enlarged scale and showing die cushioncylinders in detail; I

`Figure 4 is adiagrammaticview of the hydraulic circuit, certain of theyparts being shown in section; i L 20 Figure 5 is a longitudinal`sectional view oi a reversing valve;

Figure 6 is a sectional view taken on the line 6 6 of Figure 5;

Figure 7 lis a detail View of a manually oper- 25 able control lever; yi Figure 8 is a planview of a p ump cross head;

Figure 9 is a detail view showing the relative positions of a male and afemale die and a blank being drawn at an intermediate point in thedrawing operation, and;

Figure 10 is a view similar to' that shown in Figure 9, the parts beingshown in the positions occupied at'the end of the drawing operation.

Like numerals designate corresponding Parts in the several viewsillustrated.

Hydraulic presses have been previously built which were capable ofautomatically performing an indeterminatenumber of pressing operations;

usually employed to furnish the pressure for operating such presses, ithas heretofore not been found possible to operate these presses at ahighspeed, except in the case'of small presses where the inertia of ythemoving parts, and especially that of the pump cross head, iscomparatively small.

In connection with'such automatic presses it has been usual, to employ avariable discharge, reversible pump of the type described in U S; 5oLetters Patent No. 1,250,170, of December 18, Pumps of this type areprovided witha cross-head, the shifting of which reverses theilowof thefluid in Y the hydraulic circuit, the reversals producing thereciprocatory motion of the press platen.

While the construction of this type of pump is now well known to thoseskilled in the art, for

the sake of clearness attention is called to the fact that in such pumpsthere is usually provided a spring adapted to yieldingly hold the pumpcross head in a position permitting the pump to deliver its fulldischarge,l there being also provided either mechanical Yor pressureoperated means adapted to move said cross head against the pressure ofsaid spring, thereby progressively reducing the discharge of the pump tozero, and then progressively increasing the discharge of the pump in theopposite direction.

As stated above, when the system is comparatively small, the inertia ofthe pump cross head is also small, so that it may be quickly shifted toreverse the ow of the uid'under pressure, and a high pressoperatingvspeed may be thereby attained. It is obvious that-/where thepress used is large, and the pump cross head correspondingly large, thecross head has an inertia suflicient to oppose the shifting thereof, andto thereby cause a considerable time lag to occur between the strokes ofthe platen, which naturally is objectionable since it slows down theoperating speed of the press.

I have found that, by arranging such a pump to discharge in onedirection only, and by providing means whereby the uid discharged by thepump may be directed alternately to the pressing cylinders and to thepush back cylinders operating the press platen, it is possible to attaina high operating speed with a large press.

When operating a large hydraulic press, it is of course essential thatthe discharge of the pump be reduced as the press platen nears the endof the up and the down strokes, since aV sudden reversal of flow of thefluid under pressure when thepump is delivering its full discharge wouldresult in a, shock or water hammer in the hydraulic system, such shockbeing injurious to the various associated parts.

It is to be understood that in the description which is to follow theterm automatic operation means that kind of operation in which thereciprocatory platen continuously performs an indeterminate number ofpressing operations, and the term semi-automatic operation means thatkind of operation in which the platen performs one complete pressingcycle, and is then brought to rest in its uppermost position.

The invention mayv be embodied in various types of hydraulic presses,but in the accompanying drawings it is illustrated in connection with apress of the four column downward pressure type. Referring to thedrawings, there is shown a hydraulic press A, having a base B, astationary table C, a press head D connected to said table by fourstrain rods E, a reciprocatory platen or movable die support F, and adie cushion G. The die supportF is guided on the strain rods E in theusual'manner. An annular female die H having a lower face h and an innerdownwardly facing surface h is secured to the under side of the platen,which in effect is a movable support table and located directly over anopening therein. A circular sheet metal blank K is shown in Figures 1and 3 as being positioned on the punch shape assumed by the blank duringthe drawing operation.

The die cushion G is carried by a supporting plate I, suspended fromlugs 2 or the press frame by means of strain rods 3 threadedly connectedat their lower ends to lugs 4 on the supporting plate. A cushioninglcylinder 5 is carried by the supporting plate and is preferablypositioned directly beneath the punch I, and also carried by thesupporting plate on opposite sides of the cushioning cylinder are blankholder returning cylinders 66, equally spaced from the cushioningcylinder and-preferably of somewhat lesser diameter than the latter.Mounted for reciprocation in the cylinder 5 is a cushioning plunger orram 1, and in the cylinders 6-6 blank holder returning rams v8 8 aremounted. The rams I and 8-8 are connected at their upper ends to a yoke9. Connected to the yoke by means of pins I0 extending through openingsII in the die support or bolster plate is a blank holder or clamp- 'ingring I2 concentrically arranged around the the punch, the blank K whichis positioned on the clamping ring will be clamped between the latterand the lower face of the female die. A plurality of vertically disposedguide standards I3-I3 bolted to the bolster plate and arrangedcircumferentially around the clamping ring guidesthe said ring duringits reciprocatory movements, thus relieving the pins I0 of any lateralthrust to which said pins might otherwise be subjected.

A variable discharge pump I4 of the type above referred to is connectedto a surge tank I5 by means of a suction pipe I6, as shown in Figure 4.The discharge of the pump -is directed through a pipe line I 'I which isconnected to a reversing Valve I 8. The valve I8 also has connected toit a pipe line I9, which leads to booster cylinders 20 and to one sideof a. surge Shifting valve 2|, located in the surge tank I5, a pipe line22 which leads to push back or die returning cylinders 23 and to theother side of the surge shifting valve 2i, and apipe line 24 which leadsto and opens into the surge tank I5. The surge shifting valve 2| ispreferably mounted directly on top of a main pressing cylinder 25 and isarranged to communicate therewith by means of a port 25a. As will behereinafter described, the reversing valve I8 is adapted to direct fluidunder pressure alternately to the pressing cylinder 25 and to thediereturning cylinder 23 to effect reciprocations of `the movable diesupport F, the two-cylinders thus line 2S, and, since there are novalves in this pipe line, the cushioning cylinder and the pressingcylinder are always in direct communication, and

it is therefore apparent that the unit pressure in the cushioningcylinder will always be the same as that in the pressing cylinder. Thecushioning ram 1 is of smaller diameter than the main pressing ram 21 sothat the total pressure exerted upwardly on the cushioning ram will beat all times less than the pressure exerted upon the pressing ram, andas a result the clamping ring will be v forced downwardly by the .femaledie when .the

die descends. Because of the constant open communication between thecushioning cylinder and the main pressing cylinder 25, the totaleffective pressure exerted on the cushioning ram '8 will always bear aconstant ratio to the total effective pressure exerted on the mainpressing ram 21. In other words, when the drawing pressure is. large andresults ina marked 'tendencyy for the blank to wrinkle, the pressureexerted upon the blank by the clamping ring will also be large, andwrlnkling of the blank will be veffectively prevented. When the drawingpressure -is relatively small, the clamping pressure will also berelatively small and the blank will not be unnecessarily squeezed.

The construction and the operation of the; reversing valve I8 will behereinafter described in detail, but for the 'sake of clearness it will,for the present, be suiiicient to say that the valve is adapted to beset in either 'of -two positions, in the rst of which positions the pipeline I1 is placed in communication with the pipe line I9,

and the pipe line 22 with the pipe line 24, and in the second of whichpositions the pipe line I1 is placed in communication with the pipeline22, and the pipe line I9 with the pipe line 24.

The surge shifting valve 2| is provided with a valve casing 29 having avalve chamber 38 which communicates with the surge tank I5 by means of aport 3|, and with the main cylinder 25 of the press by means of the port25a. Slidably mounted in the chamber 30 is a balanced piston valve 32,said valve being provided at one of its ends with a tail rod 33, thetail rod being slidable in a bore 34.v 'Ihe bore 34 communicates withthe chamber 30 by means of the passage 35, and also with the pipe lineI9. The valve 32 is also provided with a second tail rod- 36 whichextends through a chamber 31 into a bore 38 in a casing 39 attached tothe casing 29, and into a chamber 49 in said casing 39, the chamber 40cornmunicating at its outer end with the pipe line 22. It may be `notedthat, when the piston valve 32v is in the position shown in the drawing,the main cylinder 25 communicates with the surge tank .I5 by means ofthe port 25a, the chamber 30 and the port 3| but, when the piston valveis caused to be shifted to the left inl a manner to be hereinafterdescribed, the cylinder 25 will communicate with the pipe linev I9 bymeans of the port 25a, the chamber 38', the passage 35, and the bore 34.

Mounted onthe top of the valve casing 29 and adapted to commmunicatewith the chamber 31 is a check valve 40, which comprises a casing 4I,ports 42, 42, and 43, and a valve ball 44 which is urged to closedposition by a spring 45, the tension of which spring may be adjusted bymeans of athreaded plug 46 for a purpose hereinafter specified. It is tobe noted that, when thevpiston valve 32 is moved to the left in theplane of the drawings, fluid contained in .the chamber 31 will,

' chamber 31 through said check valve.

Mounted on the bottom of the casing is a second check valve 41 adaptedto communicate with the chamber 31 by means of the port 48 and with thesurge tank I5 by means ofthe port 49. It is to be noted that, though nolHuid will be discharged from the chamber 31 through the valve the ball58 will be lifted from its seat by the suc- Ltion created in the chamber31, .thus allowing fluid to flow from the surge tank I5 through theports 49 and 48 into the chamber 31.

With more particular reference to the reversing valve I8, there is showninFigures 5 and 6 a valve casing 5| having a central chamber 52 and apiston valve 53 slidable longitudinally in the bore forming saidchamber, and being closely tted therein. In order to facilitate theconnecting of the control valve I8 to the pipe lines VI9 and 22, thereare provided detachable plates 54..which.are

' bolted orA otherwise attached to the valve casing -5I,` tongue andgroove connections 55 forming pressure tight joints between the plates54 and the valve casing 5|. The plates 54 are provided with threadedbores which receive the ends of the pipes I9 and 22, thereby placingsaid pipes' in communication with the valve chamber 52 by means of ports56 and 51 respectively. The pipe line I1 communicates with the valvechamber 31 by means of a port 58, and it is to be noted that movesto theright in Ithe plane of the drawingl when the piston valve 53 is in theposition shown.,`

in Figures 5 and 6 the pipe line I1 communicates with the pipe line I9by means of the port 58, the valve chamber 52, and the port 56. When thepiston valve is'` moved to the right in the plane of the drawing in,amanner to be hereinafter described, the pipe line I1 will' be placed incommunication with the pipe line 22 by means of the port 58, the valvechamber 52, and the portu 51.

In one end of the valve casing 5| is a bore 59 into which is -closelyfitted a 'ring`60 provided the pipe 24, thus placing said pipe incommunication with the valve chamber 52 by means of a port 65 whichextends through the plate 64 and the ring |50, and the passage 62. Withthe piston valve 53 in the position shown in Figures 5 and 6, the pipeline 24 communicates with the pipe line 22 by means of the port 65, thepassage 62, the valve chamber 52, and the port 51. When the piston valve53 is moved to the right from the position shown in the drawings, thepipe line 24 is placed in communication with the pipe line I9 by meansof the port 65, the valve chamber 52, and the port 56.

At one end of the piston valve 53 there is provided a rod 66 extendingthrough the valve chamber 52 and beyond the valve casing 5|, the rod 66sliding in a bore 61. provided with a suitable packing gland 68. At theouter endoLthe rod 66 there is provided a collar 69 rigidly attached tosaid rod by a pin or other suitable attaching means.

The valve casing 5| yis provided with chambers *10, 16 communicatingwith pipe lines 1|, 1| by means of ports 12, 12. The pipe lines 1|, 1|cornmunicate at all times with the pipe line I9 so that the same iiuidpressure is caused to exist in the chambers 10, 18 as in the pipe lineI9.

Adapted to slide in packing glands13 in the valve casing 5|, andprojecting into the chambers 10, are plungers 14, 14, said plungers`sliding inbearings 15 in a bracket 16 bolted to a flange 11 on thevalve casing' 5|. A cross bar 18 is attached to the plungers 14, 14 bymeans of nuts 19, 19.

Slidably mounted on the plungers 14 and the rod 66 is a cross head 88equipped with suitable bushings 8|. The plungers 14 are provided withcollars 82 adapted to abut the cross head 88 and to thereby move saidcross head to the right in the plane of the drawing when said plungersare caused to be moved to the right.

A spring loaded compressible link 83 is loosely pivoted at one end tothe cross head 88 and at its other end to a pin 84 on the bracket 16,while a second and similar link 85 is loosely pivoted at one end to thecross head 88 and at the other end is xed toy a rock shaft 86 journaledin the' bracket 16. It'is to be noted that the links 83 and 85, and thecross head 88, which in effect is Aalso a link, comprise a spring loadedtoggle, so

l center of the cross head 88 will eventually reach a point just to theright of a line connecting the centers of the pivot pin 84 andtherockshaft 86,

at which .time the toggle will quickly snap to its extreme position,whereby the cross head 88 will strike the collar 69 on the rod 66 andmove said rod and the piston valve 53 to the right. By rocking the shaft86 in a counterclockwise direction by means hereinafter described, thetoggle will be caused to move in the opposite direction, nally snappingto the left and causing the cross ,head to abut a shoulder 81 on thevrod66, thereby shifting the piston valve 53 to the left.

Mounted in a boss 88 on the bracket 16 and extending longitudinally ofthe rod 66 is a stem 89 provided at its inner end with aA shoulder 98abutting a shoulder 9| in the boss 88, a clampingnut 92 being threadedto the stem 89 and serving to hold the shoulder 98 against the shoulder9|, thereby locking the stem 89 to the boss 68. I A set screw 93 in theboss 88 prevents-the stem 89 from turning relative to said boss. 1n theinner end of the stem 89 there is provided a recess 94 permitting therod 66 and the collar 69 to move to the right, the bottom of said recesslimiting the movement of said rod and nut in that direction.

Slidably mounted on a reduced portion of the stem 89 is a collar 96"which is urged against a shoulder 91 on said stem by means of a collAspring 98. A hand wheel 99 is -threaded on the outer end of the stem 89and is adapted to' vary the expansive force of said spring.- A springseat |88 and a thrust bearing |8| are interposed between the hand wheeland the spring to facilitate the turning of said hand wheel, and a nut|82 prevents the hand wheel from being accidentally removed from thestem 89.

Referring to Figure 1, there is shown a vertically disposed operatingrod |83, slidably mounted in lugs |84 and |85 on the` stationary table Cand the press head D respectively, the downward movement Aof said rodbeing limited by a collar |86 adjustably fixed to the rod. The operatingrod |83 is constantly urged to its lowermost position by gravity andalso by means of a coil spring |81 mounted on said rod between the lug|85 and a collar |88 also on said rod. A boss |89 on the movable diesupport is arranged to slide freely on the operating rod |83. Adjustablyattached to the-rod |83 is a collar ||8 which is adapted to be engagedby the boss |89 when the movable support has reached a predeterminedhollow coupling ||1, the latter being plvotally connected at ||8 to amanually operable control lever H9. A tensioned coil spring |28interposed between the press base B and the shorter arm of the bellcrank lever tends to cause a lug |2| on said handle to abut a lug |22 onthe base B, thereby normally maintaining the bell crank lever in theposition shown in the drawing.

As clearly shown in Figure 7, there is rigidly attached to the upper endof the rod ||6 a collar |23 which is adapted to slide within the hollowcoupling ||1 and to abut the inwardly extending flange |24, therebylimiting the downward movement of the rod ||6 relative to theA coupling||1. It is apparent that, although the control lever ||9 may be swung tothe left and the rod ||6 thereby elevated, an upward movement of the rodI |6 will not cause the control lever to be moved. Thus, when the rod||6 is caused to perform a reciprocatory motion during constantoperation of the press in a manner hereinafter described, there will beno Idanger of the control lever swinging outwardly and striking theoperator.

In Figures 1, 2, and 8 there is shown a mechanism for controllingtherate of discharge of the pump. This mechanism is provided with a.vertically disposed and longitudinally adjustable operating rod |25slidably mounted in lugs |26 and |21 on the stationary tablel C and thepress head D respectively. The downward movement of said rod is limitedby collars |28 and |29 iixedly attached to the rod. The operating rod|25 is constantly urged to its lowermost position by gravity and bymeans of a. coil spring |38 mounted on said rod and interposed betweenthe lug |21 and a collar 3| on the rod. 4A boss |32 on the movablesupport is arranged to slide freely on the operating rod |25.-Adjustably attached to the rod |25 is a collar |33 which is adapted tobe engaged by the boss |32 when the movable support has reached apredetermined point in its upward travel, the rod |25 being therebylifted. Rigidly attached to the base B directly below the lug |26 is abracket |34 to which a bell crank lever |35 is'pivoted as at |36. A link|31 is pivoted to the operating rod |25 at |38 and Vto the bell cranklever |35 at |39.

A link |48 disposed at right angles to the operating rod |25 ispivotally connected to the bell crank lever at |4|. A lever |42,plvotally mounted at |43 on a bracket |44 carried by the pump,

. has one of its ends plvotally connected at |45 to the link |48. Theother end of the lever |42 is provided with a rounded head |46 which isengaged by a. cross vhead |41 on the pump |4,

whereby a. clockwise movement of the lever |42 will cause the pump crosshead to be pushed towards the center of the pump, thus decreasing thedischarge of the pump in a `manner well 'known to those skilled ih theart. As stated exerted onthe cross head by the lever |42, is removed. IOperation If it is desired that'the press operate under full automaticcontrol, the collar III! is 'adjusted in a position on the operating rodpermitting said collar to be engaged'by Atheboss |09 at the proper pointin the up stroke of the movable support, and the motor driving the pumpthen started.

Assuming 'that this adjustment of the collar I I0 has been made, thatthe motor driving the pump has been started, and that the movablesupport F is travelling downward, the various parts comprising theautomatic control mechanismwill be in the positions shown in the draw-vings, the blank K will have been placed on the punch as shown in.Flgure-1, and the operation of the press will be as follows:

Thel pump I4 is set to deliver its full dischargev of huid underpressure through the pipe line I1 into the reversing valve.|8, the fluidthen passing through the port 58, the valve chamber 52, lthe port 56,and the pipe line I9 and into the. booster cylinders 28, the fluidpressure thereby exerted in said booster cylinders causing the movablesupport to move downwardly. During lthis part of the down stroke of thesupport, liuid' from the surge tank I5 will owthrough the "port 3|, thevalve chamber 30, and the port 25a into the main cylinder 25. It is tobevnoted that, during the down stroke of the support, the fluid whichentered the die returning cylinders 23 andthe return cylinders 6, 6duringthepreceding up stroke must escape from said cylinders, the fluidescaping from'the diel returning cylin- -ders` by means of the pipe line22, the port 51,

the valve chamber 52, the passage 62, the port 65, andthe pipe line 24,which pipe line discharges said fluid into the surge tank I5, and

the fluid in the return cylinders escaping through j the pipe line s28into the die returning cylinders and thence over the same path as thefluid which was in the die returning cylinder.

When the female die H contacts 'the blank K,`

further movement of the platen and the die will be resisted, firstly',by the resistance to bending ofthe blank-'which is supported on thefixed most position to its point of contact with the punch I, and,secondly,`by the clamping ring I2 contacting the blank K, the clampingring being yieldably urged upwardly by pressure in theA cush ioningcylinder 5.l When the female die first engages the blank, the pressureinthe cushioning cylinder 5 is small, being due only to the static headlof the fluid in the surge tank I5. It is to,v be noted that, in theinterval during which the female die. is moving from its upperblank, thefull discharge of the pump is directed to the boosterv cylinders, whichare of relatively small diameter. This results in a-rapiddie travelduring the inactive portion of the down or draw'- v ing stroke, so' thata minimum of ltime is consumed in bringing thedies into actual drawingrelation.

As the drawing of the blank starts, the female die and* its movablesupport will encounter resistance to their downward travel', and thefluid pressure in the pipe lines I1 .and I9 l will build up until itreaches a predetermined value',` at which time said pressure, acting onthe tail rod 33 ofthe surge shifting valve 2|, will'ucause the.. Vpistonvalve 32 to be moved to theleft from the position shown in the drawing,thereby expelling the fluid. contained. in the chamber v31 throughvalve, and, `at the same time', said valve chamber 30 will be placed incommunication with the pipe line I9 by means of the passage 35 and thebore 34, which bore has been vacated by the tail rodv 33. Themaincylinder 25 now receives the .fluid under pressure from the valvechamber 38 through the port 25a. The movableI support, now, being forceddownwardly by the combined action of the main and booster cylinders,continues said downward movement until the resistance to drawing causesthe pressure to build up in the circuit" and then to act to move thepump cross head inwardly against the pressure of 'the cross head spring,thus ldecreasing thefrate of discharge from said pump and preventlngtheoccurrence of yshocks of waterhammer which might otherwise take placewhen the flow of fluid under pressure isreversed to start the support onits upward movement'. During the drawing .of the blank, the building upof the pressure in the main pressing cylinder 25 has resulted in aproportional increase'in pressure in the cushioning cylinder 5, theblank-being thereby clamped between the v clamping ring I2 and thefemale die by a -force proportional 'to the drawing pressure, that isthe ratio of the blank holding pressure tothe drawing pressure isconstant for all values of drawing pressure, `and wrlnkling of the blankis thereby prevented.

When the drawing operation has been completed and the`female die hasreached the posi-l tion shown in Figure 10, the blank (now drawn) willbe subjected to a finishing, or pressing, operation. The formed blankwill `be tightly pressed between the top surface i of lthe vpunch i andthe inner downwardly-facing surface h' of the female die, a very smoothfinished article,

free from wrinkles or other imperfections some` times caused by drawing,being thereby produced. This pressing of the blank between the two diesresults in a building up of the pressure in the main cylinder, and themovable support will be reversed and returned to its upper or normalposition as follows:

As has been heretofore stated, the chambers 10 are always incommunication with lthe pipev line I9 by means of the ports 12 and thepipe line 1|,

cause the cross'bar -18 to slide on the stem 8,9,

and` the collars 82 to abut the cross head 80 'andithereby move saidcross head to the right against the force exerted by the spring loadedcompressible links 83 and 85. When the vertical jso that, as the fluidpressure builds up in the center line of the cross head has reached apoint just a little'tothe left of a plane containing the centers of thepin 84 and the rock shaft 86, the` cross bar 18 will abut the collar 95,the

lplungrs 14 being thereby held against furtler' movement to the rightuntil the fluid pressure in the chambers 10 has further built up. When75' pressure of the spring 98, thus allowingv the plungers 14 to movefurther to the right, until the cross head 80 has passed the planecontaining the pin 14 and the rock shaft 86, at which time the springloaded compressible links 83 and 85 will cause the toggle to snapquickly to the right,

4the cross head 80 striking the collar 69 on the rod 66, moving said rodand' the piston valve 53 to the right.

From the foreging it is apparent that the travel ofthe platen and thefemale die is reversed upon the attainment of a definite pressure in themain pressing cylinder 25, and that the reversal is not directlydependent upon any distance control means. This characteristic will atonce be seen as an important advantage when it is remembered that diesof any depth, within reasonable limits, may be placed on the machine andoperated in the above manner withoutthe necessity of making newadjustments for each different set ofdies in order to properly controlthe length of stroke of the movable die.

Itis to be noted that, by turning the hand wheel 99 and thus varying thetension of the spring 98, the amount of pressure which must build up inthe main and booster cylinders lbefore the valve I8 is reversed may bevaried at will.

As has been descrlbed'above, when the piston valve^53 has been moved tothe right, the pipe line |1 will communicate with the pipe line 22,

and the' pipe line I9 with the pipe line 24. In this position of thevalve, the discharge of the pump is directed through the pipe lines I 1and 22 into the die returning cylinders v23 and the chamber 40 in thesurge shifting valve 2|. The fluid pressure in the chamber 40 acts onthe tailrod 36 causing the piston valve 32 to be moved to the right, inother words, to the position shown in Figure 4. While the piston valveis moving to the l right, fluid from the surge tank I5 will enter the yrin chamber 31 through the check valve 41 as hereinbefore described. Theiluidv under pressure in the die returning cylinders 23 then causes themovable support to move upwards, the iiuid contained inthe main cylinder25 then being expelled-.therefrom into the surge tank I5 through theport 25a, the valve chamber 30, and the port 3|, and the uid in thebooster cylinders 20 being expelled through the pipe line I9, thereversing valve I8, and the pipe line 24 into the surge tank I5.

Since the blarikjholder` returning cylinders 6- are in constantcommunication with the die returning cylinders by means of the pipe line28, uid will enter the return cylinders 23 during the upwardmovement ofthe platen, and will move the s 8-8 'upwardly to return the clamping y fto its upper position. The upward move merit of the 'rams s-sv islimited by theyoke s contacting with 'the bolster plate J, and the pinsIfare of. such a` length that, when the return rms have reached theirupper limit, the upper face of the clamping ring will lieinsubstantially the same plane as the upper face of the punch.

It is to be noted that, since the pressure in the pipe line I1 is lessat this time than it was at the time the movable support met resistancetoits'downward travel,l the spring on the pump cross head will returnsaid cross head to the position permitting maximum discharge by thedirection by means of the link |31, the bell crank lever |35, and thelink |40. By this movement of l the lever |42, the head |46 of saidlever forces the cross head |41 of the pump inwardly against the forceof the pump cross head spring, thereby reducing the rate of dischargefrom the pump preparatory to a. reversal of direction of travel of themovable support for the purpose stated above.

When the support has proceeded a little farther on its upward travel,and has reached a predetermined point, the boss |09 will strike thecollar ||0 'on the operating rod |03, lifting said operating rod,whereby the collar I contacts withA the arcuate projection ||4 on therocker arm ||3, causing said rocker arm tobe swung upwardly. thusturning the rock shaft 86 in a clockwise direction as viewed in Figure 1and in a counterf clockwise direction as viewed in Figure 6. Thisturning of the shaft 86 causes the compressible link 85 .which is xed tothe rock shaft to be swung to the left, whereby the cross head 80 willbe also swung to the left, during which movement the cross head willstrike the collars 82 on the plungers 14, and the shoulder 81 on the rod68, thereby returning the plungers to their inner position and thepiston valve 53 to the position shown in Figures 5 and 6; In this posi-4the female die then return to its uppermost position and stop, thecollar ||0 on the operating rod |03 isloosened and moved up into aposition in which it Will not be engaged by the boss |09. Assuming thatthe"movable support is on its downward stroke, the completion of saiddownward stroke and the start of the upwardstroke will be executed inthesame manner as that described above. When the boss |32 strikes thecollar |33 on the upward stroke o1' the support, the rod 25 willbeliftedand the pump cross head `|41 moved inwardly in the manner alreadydescribed, until said cross head has reached a point at which thedischarge of the pump is zero, the movable support then coming to rest.

To cause the movable support to descend 4to cause the dies to performanother drawing operation, the manually'operable control lever ||9 isswung to the left from the position shown in Figure 1, thereby raisingthe rod IIB, swinging thelever ||3 upwardly, and turning the rock shaft86 in a clockwise direction as viewed in' Figure 1 and inacounterclockwise direction as lviewed in Figure 6. 'The piston valve 53is thereby moved to the left in the manner described above, and the pipeline I1 will then communicategwith the pipe line I3. and the pipe line22 with the pipe line 24. It may be noted that, though the valves I8 and2| are now 'in a positionto allow fluid under pressure to produce adownward movement of the platen, the

iii.

die returning cylinders 23 with the surge tank l by means'of the pipeline 22, the valve I8, andl the pipe line 24, and thel booster`cylinders 20 with the surge tank by means of the pipe line I9, the valveI8, the pipe line I1, the pump Il, and the pipe line I6, there is nofluid pressure tending to hold the movable support up. The weight of thesupport itself will therefore cause the latter to coast downwardlyAuntil the operating rod I25`has been lowered and the pump cross head |41thereby allowed to be moved outwardly by the cross head spring,`whereupon the pump will start to discharge and the operation willproceed in the manner already described.

While one method of carrying out Amy invention has been hereindescribed, it is of course to bel understood that the details ofstructure and arrangements of parts may be variously changed andmodified without departing from the spirit and scope of my invention.

I claim:

1.A In a drawing press including a. movable die and amovable blankholder; the combination with hydraulic actuating means for moving saiddie towards said holder; loi? a source of fluid pressure connected tosaid means; hydraulic cushioning means associated with said blank holderfor yieldably urging said blank holder towards said die; and hydraulicconnections between said actuating means and said cushioning means formaintaining at constant ratio the hydraulic pressures therein.

2. In a drawing press including a reciproca tory die and a movable blankholder, the combination with hydraulic actuating means for re-vciprocating said die towards and away from said holder; of a source offluid pressure connected to said actuating means; hydraulic cushioningmeans associated with said blank holder for -vyieldingly urging said.blank holder towards said die during movement of the die towards saidholder, and for moving the blank holder towards the die whileA the dieis moving away from said holder, and hydraulic connections between saidhydraulically actuated die moving means and said hydraulic cushioningmeans for maintaining at a constant ratio the hydraulic pressurestherein. Y l

3. In a drawing press, including a press frame, the combination with apair of die supports mounted on the frame, one oi' said supports beingmovable towards and away from the other: of hydraulic actuating meansEfor effecting alternate drawing and return strokes of said movablesupport, said actuating means including a main pressing cylinder; a diefixed to each support; a source of fluid pressure; means forming withthe pressing cylinder and with said source of fluid pressure a hydrauliccircuit; a blank holder adapted to clamp a blank against oneof the dies;va cushioning cylinder; hydraulically actuated means mounted forreciprocation in, said cushioning cylinder and connected to s'aid blankholder for resisting kmovement of said holder during the drawingstroke;-hydraulic connections betweenl the pressing cylinder and thecushioning cylinder for maintaining proportionate pressures therein-andcircuit controlling Cil meansoperatively connected with the circuit forcausing said hydraulically actuated means to effect' alternate drawingand return strokes of the Ymovable support.

4. In adrawing press, including a press frame, y

, 'adapted to clamp a blank against one of the dies,

said holder being also adapted to be moved away from its normal positionby the die during the drawing stroke of the latter; a cushioningcylinder; hydraulically actuated means mounted for reciprocation. insaid cushioning cylinder and connected to said blank holder forresisting movement of said holder during the drawing stroke; hydraulicconnections'between the press- 1 ing cylinder'and the cushioningcylinder for maintaining proportionate pressures therein; hydraulicallyactuated means associated with the blank holder and connected to -said`hydraulic circuit for returning said holder to its normal positionduring the return stroke of the movable l support; and 'circuitcontrolling means operatively connected with the circuit for causingsaid hydraulically actuated means to effect alternate drawing and returnstrokes of the movable support. 4

5: In a drawing press, including a press frame, the combination swith apair of die supports mounted on the frame, one of said supports beingmovable towards and away from the other; of

' hydraulic actuating means for eiecting alternate drawing and returnstrokes of said movable support; said actuating means including a mainpressing cylinder, and a die returning cylinder; a

,die xed to each support; a source of fluid pressure; means forming withthe pressing cylinder and with said source of fluid pressure a hydrauliccircuit; a blank holder normally occupying a position at rest and beingadapted to clamp a blank against one of the dies; a cushioning cylinder;hydraulically actuated means mounted for reciprocation in saidcushioning cylinder and connected to ksaid blank holderl for resistingmovement of said holder d ing the drawing stroke; hydraulic connectionetween the pressing cylinder and the cushioning cylinder for maintainingproportionate pressures therein; a blank holder returning cylinder;hydraulically actuated means mounted for reciprocation in said blankholder 4returning cylinder and'connected to the blank holder forvreturning the latter toits normal position during the return stroke ofthe the combination with abolster plate connected to the frame andhaving an opening; of ,a die connected to the upper face of the bolsterplate; a movable die support mounted on the frame vforperformingvdrawing and return strokes respectively towards andawayiromsaid die; a second die mounted on said support; hydraulic actuating,said support, said actuating means including a main pressingA cylinder;a source of fluid pressure; means forming with the pressing cylinder andwith said source of fluid pressure a hydraulic circuit; a cushioningcylinder connected to said frame below the bolster plate; cushioningmeans mounted in said cushioning cylinder for reciprocatory movements; ablank holder adapted to clamp a blank against the moving die, said blankholder beingk arranged in cooperative relation with the die on thebolster plate; means extending through the opening and connected to saidreciprocatory cushioning means and to the blank holder for resistingmovement of said holder during the drawing stroke; hydraulic connectionsbetween the pressing cylinder and the cushioning cylinder formaintaining proportionate pressures therein; and circuit controllingmeans for causing said hydraulic actuating means to eiect drawing andreturn strokes of the movable support.

'7. In a drawing press'including a press frame, the combination with abolster plate connected to the frame and having openings; of a dieconnected to the upper face of the bolster plate; a movable vdie supportmounted on the frame for performing drawing -and return strokesrespectively towards and away from vsaid die; a second die mounted onsaid; support; hydraulic actuating ,'means for effecting reciprocatorymovements of said support, said actuating means including a mainpressing cylinder and a die returning cylinder; a source of fluidpressure; means forming with the pressing cylinder and with said sourceof fluid pressure a hydraulic circuit; a cushioning cylinder connectedto said frame below the bolster plate; a cushioning ram mounted in saidcushioning cylinder for reciprocatory movements; a blank holderreturning cylinder connected to the frame and disposed adiacent the lcushioning cylinder; a ram mounted for re'ciprocatory movements in saidreturning cylinder; a blank holder for clamping a blank against themoving die and arranged in cooperative relation n with the die on thebolster plate; means extending through the'openings in the bolster plateand connecting said blank holder to the blank holder -to the frame andhaving openings; of a die connected to the upper face of the bolsterplate; a movable die support mounted on the frame for performing drawingand return strokes respectively toward and away from said die; a seconddie mounted on said support; hydraulic actuating means for effectingreciprocatory movements of said support, lsaid actuating means includinga main pressing cylinder and a die returning cylinder; a source of fluidpressure; means forming with the pressing cylinder and with said sourceof fluid pressure a hydraulic circuit; a cushioning cylinder connectedto said frame below the bolster plate; a cushioning ram mounted in saidcushioning cylinder for yreciprocatory movements; a blank holderreturning cylinder coni nected to the frame and disposed adjacent thecushioning cylinder; a ram mounted for reciprocatory movements in saidreturning cylinder; a blank holder for clamping a blank against themoving die and arranged in cooperative relation with the die 'on thebolster plate; a yoke connected to said'cushioning ram and to said blankl.holder returning ram, said yoke being arranged in substantialparallelism with the bolster plate, and being adapted to engage saidplate to limit the movement of said rams in one direction; meansextending through the openings in the bolster plate and connecting theblank holder to said yoke; hydraulic connections between the maintainingproportionate pressures therein to urge the blank holder against themoving die;

hydraulic connections between the die returning cylinder and the blankholder returning cylinder; and circuit .controlling means for causingsaid hydraulic actuating means to effect drawing and return strokes ofthe movable die.

9.` In a drawing press, including a press frame, the combination with apair of die supports mounted on the frame, one of said supports beingmovable towards and away from the other; of hydraulic actuating meansfor effecting alternate drawing and return strokes of said movablesupport, said actuating means including a main pressing cylinder; a diefixed to each support; a

source of iiuid pressure; means forming with the pressing cylinder andwith said source of fluid pressure a hydraulic circuit; a blank holderadapted to clamp a blank against one of the dies; a cushioning cylinder;hydraulically actuated means mounted for reciprocation in saidcushioning cylinder and connected to said blank holder for resistingmovement of said holder during the drawing stroke; hydraulic connectionsbetween the pressing cylinder and the cushioning cylinder formaintaining proportionate pressures therein; circuit controlling meansoperatively connected with the circuit for reversing the direction offluid travel to reciprocate the movable support; and means responsive tothe uid pressure in the circuit for decreasing the speed of travel ofthe movable support when said support approaches the limit of itsdrawing stroke.

10. In a drawing press, `including ,a press framle, the combination witha pair of die supports mounted on the frame, one of said supports be- Ying movable towards and away from the other; of hydraulic actuatingmeans for effecting alternate drawing and return strokes of said movablesupport, said actuating means including a main pressing cylinder; a dieiixed to each support; a source of fluid pressure; means forming withthe pressing cylinder and with said source of fluid pressure a hydrauliccircuit; a blank holder adapted to clamp a blank against one of thedies; a cushioning cylinder; hydraulicallyactuated means mounted forreciprocation in said cushion? ing cylinder and connectedrto said blankholder for resisting movement of said holder during the drawing stroke;hydraulic connections between the pressing cylinder and the cushioningcylinder for maintaining proportionate pressures therein; meansoperatively connected in the circuit and responsive to the fluidpressure therein for reversing the direction of fluid travel upon thebuilding up in the circuit of a predetermined pressure; and meansactuated by the movable4 support and operable at the end of the returnluid pressure a hydrauliccircuit; a blank holder adapted to clamp a blankagainst one of the dies; a cushioning cylinder; hydraulically actuatedmeans mounted for reciprocation in said cushioning cylinder andconnected to said blank holdl er for resisting movement of said holderduring the drawing stroke; hydraulic connections between the pressingcylinder and the cushioning cylinder for maintaining proportionatepressures therein; means operatively connected in the cir- 'cuit andresponsive to the fluid pressure therein for reversing the direction offluid travel when the drawing stroke has been completed; and meansVactuated by the movable support and operable at the end of the returnstroke 'for reversing thel direction of fluid travel.

12. In a drawing press, including a press frame, the combination with apairof die supports mounted on the frame, one of said supports beingmovable towards and away from 'the other; of hy. draulic actuating meansfor effecting alternate drawing and return strokes of said movablesupport, said actuating means including a main pressing cylinder; a diexed to each support; a source of iiuid pressure; means forming with thepressing cylinder and with said source. of iiuid pressure a hydrauliccircuit; a blank holder adapted to clamp a blank against one of thedies; a cushioning cylinder; hydraulically actuated means mounted forreciprocation in said cushioning cylinder and connected to said blankholder for resisting movement of said holder during the` drawing stroke;hydraulic connections between the pressing cylinder and the cushioningcylinder for maintaining proportionate pressures therein;

means operatively connected in the circuit andi the combination with apair of die supports mounted on the frame, one of said supports beingmovable towards and away from the other; of hydraulic actuating mearisfor eiecting alternate drawing and return strokesof said movablesupport, said actuating means including a main pressing cylinder; a dieiixed to each support; a `sourceof fluid pressure; meansl forming withthe pressing cylinder and with said source oi.' fluid pressure ahydraulic circuit; a blank holder adapted to clamp a blank against oneof the l dies; a cushioning cylinder; hydraulically-actuated meansmounted for reciprocat'ion in said cushioning cylinder and connected tosaid blank holder for resisting movement of said holder during thedrawing stroke;l hydraulic connections between the pressing cylinder andthecushioning cylinder for maintaining proportionate pressures therein;circuit controlling means operatively connected with the circuitforreversing the direction of iiuid travel to reciprocate the movablesupport; and means actuated by the movable support for decreasing thespeed of travel of said support when the latter approaches the limit ofits return stroke.

14. In a drawing press, including a press frame, the combination with apairof die supports mounted on the frame; one of said supports beingmovable towards and away from the other; of hydraulic actuating meansfor eiecting alternate drawing and return strokes of said movablesupport, said actuating means including. a main pressing cylinder, a dieiixed to each support; a source of uid pressure; means forming with thepressing cylinder and with said source of iluid pressure a hydrauliccircuit; a blank holder ada'pted to` clamp a blank against one of thedies; l

' therein; circuit controlling means operatively connected with thecircuit for reversing the direction of fluid travel to reciprocate themovable support; means responsive to the iiuid pressure in the circuitfor decreasing the. speed of travel of the movable support when saidsupport approaches the limit oi its drawing stroke; and means actuatedby the movable support for decreasing the speed of travel of saidsupport when thev latter approaches the limit of its return stroke.

15. Ina drawing press including a press frame, the combination with apair of die supports mounted on the frame; one of said supports beingmovable towards and away from the other; of hydraulic actuating meansfor effecting alternate drawing and return strokes of said movablesupport, said actuating means including a main pressing cylinder and adie returning cylinder; a die xed to each support; a source of fluidpressure; means forming with the pressing cylinder and with said sourceoi fluid pressure a hydraulic circuit; a blank holder normally occupyinga po- CTI ment of said holder during the drawing stroke;

hydraulic connections between the pressing cylinder and the cushioningcylinder for maintaining proportionate pressures therein; -a blank`holder` returning cylinder; hydraulically actuated means mounted forreciprocal-,lon in said blank holder returning cylinder and connected tothe blank holder for returning the latter to its no1'- mal positionduring uthe, return stroke of the 'movable support; hydraulicconnections between the die returning cylinder and the blank holderreturning cylinder; and circuit controlling means operatively connectedin the circuit for reversing the direction of fluidtravel to alternatelydirect iluid under pressure into the pressing cylinder and then into thedie returning cylinder.

16. Ina drawing 'press including a pressirame, a combination with a.pairof die supports mountagainst one of the dies; a cushioning cylinder;

hydraulically actuated means mounted for reciprocation'in saidcushioning cylinder and connected to said blank holder for resistingmovement of said holder during the drawing stroke; hydraulic connectionsbetween the pressing cylinder and the cushioning cylinder formaintaining proportionate pressures therein; a blankv holder returningcylinder; hydraulically actuated means mounted for reciprocation in saidblank holder returning cylinder and connected to. the blank holder forreturning the latter to its normal position during the return stroke ofthe movable support; hydraulic connections between the die returningcylinder and the blank holder returning cylinder; and circuitcontrolling means operatively connected in the circuit for reversing thedirection of fluid travel to alternatelyl direct fluid under pressureinto the pressing cylinder and then into the die returning cylinder,said circuit controlling means including means responsive to the fluidpressure in the pressing cylinder for reversing thedirection of fluidtravel upon attainment of a predetermined pressure in the presssure;means forming with the pressing cylinder and with said source of fluidpressure a hydraulic circuit; .a blank holder` normally occupying aposition at rest and being adapted to clamp a blank against one of thedies; a cushioning cylinder;

hydraulically actuated means mounted for reciprocation in saidcushioning cylinder and connected to said blank holder for resistingmovement of said holder during the drawing stroke; hydraulic connectionsbetween the pressing cylinder'and the cushioningcylinder for maintainingproportionate pressures therein; a blank holder. returning cylinder;hydraulically actuated means mounted for reciprocation in saidblankholder returning cylinder and connected to the blank holder forreturning the latter to its normal pol sition during the return stroke.of thel movable support; hydraulic connections between the die returningcylinder and the blank holder returning cylinder; circuit controllingmeans operatively connected in the circuit for reversing the directionoffluid travel to alternately direct fluid under pressure into thepressing cylinder and then into the die returning cylinder, said circuity controlling means including means responsive to the fluid pressure inthe pressing cylinder for reversingl the direction of uid travel uponattainment of a predetermined pressure in the pressing ed on the frame,one of said supports being movbeing performed; and means actuated by themovable support and operable when the support approaches the end of thereturn stroke for reversing the direction of fluid travel.

18.y In a drawing press including a press frame, the combination with apair of die supports mounted on the frame, one of said supports beingmovable towards and away from the other; of hydraulic actuating meansfor effecting alternate drawing and return strokes of said movablesupport, said actuating means including a main pressing cylinder and adie returning cylinder; a die fixed to each support; a source of fluidpressure; means forming with the pressing cylinder and with said sourceof fluid pressure a hydraulic circuit; a blank holder normally occupyinga position at rest and being adapted to clamp a blank against one of thedies; a cushioning cylinder; hydraulically actuated means mounted forreciprocation in said cushioning cylinder and connected to said blankholder for resisting movement of said holder during the drawing stroke;hydraulic lconnections between the pressing cylinder and the cushioningcylinder for maintaining proportionate pressures therein; a blank holderreturning cylinder; hydraulically actuated means mounted forreciprocation in said blank holder returning cylinder and connected tothe blank holder for returning the latter to its normal position duringthe return stroke of the movable support; hydraulic connections-betweenthe die returning cylinder and the blank holder returning cylinder;circuit controlling means operatively connected in the circuit forreversing the Adirection of fluid travel to alternately direct fluidunder pressure into the pressing cylinder and then into the diereturning cylinder, and means responsive to the fluid pressure in thepressing cylinder g and operable upon attainment of a predetermined.pressure therein for reducing the rate of flow of fluid into thepressing cylinder when the movable support approaches the end of itsdrawing stroke.

19. In a drawing press including a press frame, the combination with apair of die supports mounted on the frame, one of said supports beingmovable towards and away from the other; of hydraulic actuating meansfor effecting alternate drawing and return strokes of said movablesupport, said actuating means including a main pressing cylinder and adie returning cylinder; a die fixed to each support; a source of fluidpressure; means forming with the pressing cylinder and with said sourceof fluidpressure a hydraulic circuit; a blank holder normally occupyinga position at rest and being adapted to clamp a blank against one of thedies; a cushioning cylinder; hydraulically actuated means mounted forreciprocation in said cushioning cylinder and connected to said blankholder for resistingmovement of said holder during the drawing stroke;hydraulic 'connections between the pressing cylinder and thecushioningcylinder for maintaining proportionate pressures therein; ablank holder returning cylinder; hydraulically actuated means mountedfor reciprocation in said -blank holder returning cylinder and connectedto the blank holder for returning the latter to its normal positionduring the return stroke of the movable support; hydraulic connectionsbetween the die returning cylinder andthe blank holder returningcylinder; circuit controlling means operatively connected'in the circuitfor reversing the direction of fluid travel to alternately direct fluidunder Vpressure cylinder while thev drawing stroke of said die is intothe pressing cylinder and then into the die 75 returning cylinder; andmeans actuated by the movable support for decreasing the rate of ow ofiluid into thedie returning cylinder when the movable support approachesthe end of its Jreturn stroke.

20. In a drawing press, the` combination with a main ram; of acooperating main cylinder; a blank holder mounted for movements inopposition to said rain to engage and hold a blank; a blank holdercushioning cylinder; a ram connected to said blank holder and mountedfor reciproc toryv movements in said cushioning cylinder; and' foreciprocatory movements and being connected to saidmovable die;` acushioning cylinder,

a ram mounted therein for reciprocatory movements and being connected tosaid blank holder for yieldably urging the latter towards said mov-jabledie to engage and hold a blank; means for supplying fluid under pressureto said main cylinder; and a hydraulic connection between the cushioningcylinderand the main cylinder for maintaining at a constant ratio thehydraulic pressures therein.- 22. A method ior shaping metal blankswhich consists in drawing the blank to be shaped between cooperatingdies, one of whichis movable and the other stationary, moving themovable die by hydraulic means, clamping a portion of the blank againstonly the movable dieby hydraulic means, and maintaining a free anddirect interfiow of pressure fluid between the hydraulic drawing meansand the hydraulic clamping means, whereby t transmit pressuretherebetween in substantially undiminished condition, said interilow ofpressure. iluid serving to clamp said blank during the drawing operationby a pressure which bearsl a constant ratio to the drawing pressure.

WALTER ERNST.

